What does 'CH' mean on a car?

[VanPaul]

On a car, 'CH' stands for the water temperature gauge. The water temperature indicator light is used to display the temperature of the coolant inside the engine, with different colors indicating different conditions: blue indicates low water temperature, red indicates high water temperature, and no light indicates normal operation. The car's water temperature gauge shows whether the engine's cooling system is functioning properly. It consists of a pointer, a scale, and the letters 'C' and 'H'. The purpose of the water temperature gauge is to indicate the temperature of the coolant in the water jacket while the engine is running, with the scale measured in degrees Celsius. When starting the engine, the water temperature gauge should indicate no less than 50 degrees Celsius. During normal driving, the normal reading on the water temperature gauge should be between 70 and 90 degrees Celsius.